p.1 #1 · Program mode versus manual in flash photography
Up til recently I have set my D300 to manual mode when using an SB800. I usually set a shutter speed of 1/125 and adjust the aperture on the fly depending on the distance to subject. The strobe is set to TTL FP. This can be a bit of a hit or miss with some over and under exposures.
The last couple of times I set the camera to Program mode and the camera seemed to do a more consistent job with the exposure. The scenarios are social events where the people are moving around at various distances from the camera.
Is "P" a more reliable mode than "M" or do I need to do a better job in Manual mode?
p.1 #2 · Program mode versus manual in flash photography
If Program mode is making better choices than you can on the fly, then use it. You are able to choose the aperture and shutter speed yourself and it could match whatever Program gives you. Manual gives you the choice of control. Program is likely choosing whatever your e2 Flash Shutter Speed is and then likely fiddling with the aperture (most likely it is choosing maximum aperture if it's dark). What's your strategy in manual for this situation?
Usually, I set my camera to maximum aperture (say f/2.8) unless it's a group shot and I increase it only enough to get everyone in focus. Then I set my shutter to around 1/60 to 1/250 depending on the movement in the scene and how I want to portray it. Then, I set ISO between 400 and 3200 to get the amount of ambient I want and to save my flash for firing full power every time.
p.1 #3 · Program mode versus manual in flash photography
Paul, it looks like your main variable is the ISO as opposed to aperture. I usually shoot at 400 but maybe I'll try going higher and leave the aperture wider. My e2 flash speed is set to 1/60 but there are times when I really need either 1/125 or 1/250.
p.1 #4 · Program mode versus manual in flash photography
With flash, my main variable is ISO if I am use TTL, yes. What ISO does Program choose out of curiosity? If there are times you need 1/125 or 1/250, I'd suggest keeping manual because you won't get such control with program mode if you're changing between 1/60 and 1/250. Do you often need to change aperture in your situation?
p.1 #5 · Program mode versus manual in flash photography
I don't think that Program mode adjusts the ISO. I had mine set at 400 and it stayed that way the whole time. In Manual mode I usually use f/5.6 @ 1/125, ISO400, but sometimes close down to f/8 if the subject is very close or widen to f/4 or 2.8 if I shooting a large room full of people.
p.1 #6 · Program mode versus manual in flash photography
The flash doesn't have to work as hard at a higher ISO. Why change, if your method gives desired results.
Personally, I shoot 2 stops under the ambient reading and let the flash light the subject. It comes down to getting the flash level correct for the mood you desire. There are many ways to control the ambient light. I find shooting in M gives me more options than any other option. I often use similar setting to Paul K, but, it is all situational.
p.1 #7 · Program mode versus manual in flash photography
I'm not an expert in flash photography but generally I get consistent results when I use it. When indoor I always shoot in M, fixed ISO, rear curtain, iTTL. I found myself very conservative regarding aperture, for most situations being at f4 or f5.6, only when I want a shallow DOF I go wider and almost never at f8. I also find myself keeping the shooter at extremes... being very unusual to shoot at 1/125. If I want more ambient I go usually with 1/60 playing also a bit with ISO (if necessary) and for certain situations I want to kill the ambient light so I keep as low as possible the ISO and the shooter at the maximum sync speed of the camera (usually 1/250). Particularly for my family events I acquired almost for nothing a low mileage D70s just to use it with flash up to 1/500s. This because in my living & dinning area my wife installed some crazy orange lights that destroys any attempt to involve ambient light in the shoot. Believe me or not but with my D70s at the native sync speed of1/500s I get better results than with my D600 at 1/200s in that ambient. Once I established the amount of desired ambient light the only change I do sometimes is to simply adjust a bit the flash exposure and I am settled. iTTL does the job commanding the power of the flash in regard to the subject.
Last but not the least... I wonder if your inconsistent results are not related with TTL FP setting. If I know right in this mode, the flash duration is stretched so that it fires continuously for the full curtain travel time. Usually is intended for a faster shooter time and when you use it you lose power and distance. I have no idea how it really works when you use FP at slower shooter times... but if is the same behavior the flash duration is stretched to the whole 1/60s instead to be just a fraction. For closer subjects this may work but distant subjects will be underexposed. This is just a supposition but it deserves to try the plain iTTL to see how it works.
Good luck!
P.S. There are situations when I go in P mode with flash... When I am in a hurry having not time to do my tests I put camera in P and flash in iTTL and I fire... working only on FEC. Usually camera does a good job but only when the ambient light is not crazy. If I want to control the ambient light P is not a valid solution.
p.1 #8 · Program mode versus manual in flash photography
Mishu01
Auto FP (aka high speed sync) does not do anything until you set the shutter speed faster than the camera's sync speed. It's safe to just leave on all the time. Note that Auto FP does not "stretch" flash durations. The flash duration is a function of the flash design and the power output requested, and for the SB-800 it will be always be higher than something on the order of 1/1000 (and going to much faster speeds at lower flash power). The way Auto FP works: If you set your shutter speed slower than the sync speed, the flash is able to pop once in the brief interval when both shutter curtains are fully open. When you go faster than the sync speed, both shutter curtains are not fully open together at the same time - they are traveling across the frame exposing a sliver as they whiz by. Auto FP instructs the flash to pulse (at lower power) while this is happening so it puts light on multiple slivers as the shutters travel. The downside to this is a big reduction in effective flash power.
graham_martin
I'm struggling to understand your flash shooting approach (eg. setting a shutter speed and adjusting the aperture depending on distance to subject, but you are using TTL flash). I bet you don't do that when you're shooting with no flash. Because of your concern over distance to subject and your mention of aperture being your "main variable" it kind of sounds like you are confusing some techniques used when people use manual flash (where you set the flash power manually - has nothing to do with manual exposure mode on your camera). The old line "aperture controls flash, shutter controls ambient" was never a fully correct statement anyway, but it is completely wrong when you are using TTL flash.
Program and manual exposure mode (and shutter and aperture priority too) are just different ways to get to the same place: Adjusting ISO, aperture, and shutter speed for the ambient part of your exposure. Those are always your 3 variables. When you use TTL flash, the flash will fire a preflash before the shutter opens and the camera will measure and try to set the flash power to correctly expose your subject.
If program is giving you better results, it is likely because it is choosing more light for your ambient exposure (eg. slower shutter speeds, and more open apertures). If you are manually choosing 1/125 at f/8 indoors, that is likely going to be a very black photo if you were turn your flash off. Not good.
My suggestions:
1 - When using TTL flash, consider there being two exposures in your photo, the ambient portion which YOU are selecting (ISO, aperture, shutter) and the flash portion which you are letting the camera and flash determine to correctly light the subject.
2 - Consider where the light is going to hit your subject from (bounce off a ceiling slightly behind you if can, or off a wall or ceiling up and to the side of the subject, etc.).
3 - Adjust your ambient and flash exposures if you don't like the result. Pay attention to the ambient portion of your exposure for what you want the background to look like. Perhaps bring it down a stop - experiment with it. Adjust FEC if you want to adjust the flash power on your subject. Select apertures that you want (eg. don't just adjust based on distance to subject), shutter speeds that make sense (remember you can go pretty slow in dark conditions if the quick flash pulse is doing all the work), and ISO to give you the ambient that blends in nicely. Season with FEC if the subject is too bright/dark.
p.1 #9 · Program mode versus manual in flash photography
wellsjt wrote: Mishu01
Note that Auto FP does not "stretch" flash durations. The flash duration is a function of the flash design and the power output requested, and for the SB-800 it will be always be higher than something on the order of 1/1000 (and going to much faster speeds at lower flash power). The way Auto FP works: If you set your shutter speed slower than the sync speed, the flash is able to pop once in the brief interval when both shutter curtains are fully open. When you go faster than the sync speed, both shutter curtains are not fully open together at the same time - they are traveling across the frame exposing a sliver as they whiz by. Auto FP instructs the flash to pulse (at lower power) while this is happening so it puts light on multiple slivers as the shutters travel. The downside to this is a big reduction in effective flash power.
Maybe is a difference in terminology between us but AutoFP really "stretch" the flash duration. In the normal way you are right, the flash duration is an instantaneous burst of about 1/2000s (depending on flash type and manufacturer) but in AutoFP we have a different story. Nikon explain this way:
"When Auto FP High Speed Sync is selected, the flash will fire for the duration of the shutter curtain's travel, thus syncing with the camera's shutter speed when that speed is set higher than the camera's normal sync speed." (Quoted from here.
So, for a shutter speed of 1/60s we have a burst of light of about 1/2000s happening at the beginning, right after the opening of the first curtain or at the end right before the closing of the second curtain. In AutoFP mode for a shutter speed of 1/500s we have the flash emitting a continuous light of 1/500s (which is four times longer than 1/2000) but of reduced power. Of course if we use a very small shutter speed, i.e. 1/4000s that continuous light will last shorter than the normal burst and the loss of power is much higher. It's true that this continuous light is based on a series of very fast pulses... but really there is no break in between so the output is really continuous.
"This change from a high-energy near-instantaneous burst of light (normal flash), to the short period of continuous light (high-speed flash sync)."
Again if in normal use the flash duration is of about 1/2000s, in AutoFP the flash duration is "stretched" to the value of the shutter speed we are using, expanding up to 1/250s or compressing up to 1/8000s on most cameras.
This is just the technical side... in fact after searching a bit I also found that AutoFP works only when we use a shorter shooter time than the sync speed so there is no influence on the output if you always keep the camera in AutoFP when shooting in larger shooter times than the sync speed.
p.1 #10 · Program mode versus manual in flash photography
Mishu01
In your post earlier you wondered if auto FP was playing a role at low shutter speeds, and you said "I have no idea how it really works when you use FP at slower shooter times... but if is the same behavior the flash duration is stretched to the whole 1/60s instead to be just a fraction."
I was just pointing out to you that auto FP doesn't do anything at speeds lower than the sync speed (so it doesn't stretch to 1/60 s) and I explained about how it pulses the flash at speeds higher than the sync speed. It sounds like you have looked up similar info and we agree so that's cool.
